Considerable art has been developed in connection with thickened hypochlorite solutions useful in a variety of applications including hard surface cleaners, disinfectants, drain cleaners and the like. The efficacy of such compositions is greatly improved by higher viscosity of the composition, for example, to increase the residence time of the composition, especially on non-horizontal surfaces.
In addition, thickening of such liquid compositions is desirable in order to minimize splashing during pouring or application of the composition. At the same time, consumer preference for a thickened product has also been well established. In any event, the term "liquid bleach composition" is employed below to refer generally to liquid compositions intended for bleaching, cleaning, clearing of drains and other related purposes within applications such as but not limited to those summarized above.
The following references disclosed a variety of thickeners for hypochlorite bleach solutions. At the same time, these references disclosed such liquid bleach compositions including various other compounds such as alkyl ether sulfate specifically to serve as surfactants or cosurfactants within the thickened hypochlorite bleach compositions. The importance of this distinction will be apparent in connection with the present invention as summarized below.
For example, U.S. Pat. No. 4,337,163 issued June 29, 1982 to Schilp disclosed thickened bleach compositions containing as a thickening agent 0.5-5% by wt. of a mixture of (1) a hypochlorite-soluble first detergent active compound selected from the group consisting of tertiary amine oxides, betaines, quaternary ammonium compounds and mixtures thereof, and (2) a second detergent active compound selected from the group consisting of surfactants including an alkali metal C.sub.10-18 alkyl ether sulfate containing 1-10 moles of ethylene oxide and/or propylene oxide and mixtures thereof, the weight ratio of the first and second compounds being from 75:25 to 40:60, the composition further comprising from 50-350 m mol/kg of a buffer salt selected from a further defined class. The tertiary amine oxide of the first group is the preferred thickener for the composition. (Also see related EP 030401.)
The above reference is generally representative of a number of other references disclosing the use of alkyl ether sulfates in surfactant systems for thickened hypochlorite solutions. For example, U.S. Pat. No. 4,388,204 to Dimond and Murphy disclosed a thickened composition with a surfactant mixture of 10-50% sarcosinate; 3-40% alkyl ether sulfate and 30-75% alkylsulfate. Carlton, et al. in EP 137871 disclosed a thick hypochlorite solution in which 0-3% of the composition was a surfactant comprising 80-99.9% amine oxide and 0.1-20% of an anionic surfactant selected from a group including alkyl ether sulfate.
LaCroix, et al., in WO86/01823, disclosed a thickened hypochlorite solution with less than 4% amine oxide and one or more cosurfactants selected from the group of sarcosinate, alkyl ether sulfate and alkylsulfonate in amounts less than that recited for amine oxide. EP233666 to Vipond, et al. disclosed a hypochlorite solution with a C.sub.8-20 soap precursor for in situ development of viscosity and amine oxide which could allegedly be replaced by one of a number of hypochlorite soluble surfactants including alkyl ether sulfate.
U.S. Pat. No. 4,588,514 issued to Jones, et al. disclosed a thickened hypochlorite solution with a surfactant system including relatively large amounts of amine oxides, soaps or sarcosinates for thickening and a lesser amount of alkyl ether sulfate for storage stability. Stoddart U.S. Pat. No. 4,576,728 also disclosed a thickened hypochlorite solution with amine oxide, optionally betaine in an amount equal to the amine oxide and an anionic surfactant selected from a group including alkyl ether sulfate and forming 0.1-20% of the total surfactant. (Also see related EP204472.)
JP 57168999 disclosed hypochlorite solutions thickened with expansive clay and including a surfactant such as alkylphenylether sulfate.
EP79697 to Francis employed C.sub.13-18 alkyl dimethylamine oxides to thicken hypochlorite solutions with ionic strengths greater than 3g-mol/liter. EP110544 to Nelson employed C.sub.14 or greater alkyl amine oxides and added salt to thicken bleach. Extra salt was not needed if C.sub.16 or greater alkyl amine oxide were present but a shorter chain amine oxide was also needed. From a practical point of view, this is considered the same as employing two different surfactant types.
A variety of thickeners found suitable for use with hypochlorite solutions have been disclosed for example by Rupe, et al. in U.S. Pat. No. 4,116,851 which disclosed a clay thickened hypochlorite bleach which could also include other thickening agents of a polymeric type such as polystyrene, polypropylene, polyethylene or copolymers of styrene with, for example, acrylate, maleate or vinyl acetate. A similar variety of additional thickeners were disclosed by Leikhim in U.S. Pat. No. 4,116,849.